Nucleophiles fluorinated, epoxide reaction

Then, nucleophilic aromatic substitution was applied for the synthesis of l,2,4,6,7,9-hexafluoro-l,4-dibenzodioxin from 2,3,4,6-tetrafluorophenol in the presence of sodium /-butylate <1995JFC(73)265>. In a similar way, cyano-1,4-dibenzodioxins and cyano-l,4-dibenzodithiins have been synthesized by fluorine displacement reactions with catechols <2001NJC379, 2001NJC385>. In accordance with a similar mechanism, the synthesis of spiro (l,4-benzodioxin-2,4 -piperidines) 205 and spiro (l,4-benzodioxin-2,3 -pyrrolidines) 206 have been developed from alcohols 207 and 208, respectively, both of them being obtained from 2-fluorophenol 210 with the corresponding epoxide 209 (Scheme 18) <2003SL813>. 

Nucleophilic Reactions. The strong electronegativity of fluorine results in the facile reaction of perfluoroepoxides with nucleophiles. These reactions comprise the majority of the reported reactions of this class of compounds. Nucleophilic attack on the epoxide ring takes place at the more highly substituted carbon atom to give ring-opened products. Fluorinated alkoxides are intermediates in these reactions and are in equiUbrium with fluoride ion and a perfluorocarbonyl compound. The process is illustrated by the reaction of methanol and HFPO to form methyl 2,3,3,3-tetrafluoro-2-methoxypropanoate (eq. 4). 

Polyfluoroalkyl- andperfluoroalkyl-substituted CO and CN multiple bonds as dipolarophiles. Dmzo alkanes are well known to react with carbonyl compounds, usually under very mild conditions, to give oxiranes and ketones The reaction has been interpreted as a nucleophilic attack of the diazo alkane on the carbonyl group to yield diazonium betaines or 1,2,3 oxadiazol 2 ines as reaction intermediates, which generally are too unstable to be isolated Aromatic diazo compounds react readily with partially fluorinated and perfluorinated ketones to give l,3,4-oxadiazol-3-ines m high yield At 25 °C and above, the aryloxa-diazolines lose nitrogen to give epoxides [111]... 

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